The present invention relates to a mounting press for metallographic samples and particularly to an improved seal structure for the molding chamber.
Mounting presses are employed to mold a thermoplastic or thermosetting material around typically a metallic specimen for ease of handling in subsequent polishing and analyzing processes. Such mounting presses include a cylindrical mold chamber into which an upper closure ram and a lower hydraulically driven ram extend, such that the molding material and sample are held and compressed between the rams.
The standard upper closure ram uses a handle to move a radially sealing upper ram into the bore of the molding cylinder at the top. This mechanism is then locked into place with a quarter turn, bayonet-type device or by using coarse threads. This style of enclosure requires considerable manipulation by the operator especially if they have to turn the mechanism to engage threads. Opening of this type of closure is also difficult since, during the molding process, pressure builds up between the lower ram and the removable, upper closure ram of the mold cylinder. This pressure on the quarter turn device or the threads makes it very difficult for the user to spin the mechanism open. Regularly a length of pipe or some other type of lever must be used to gain a mechanical advantage to open the mold cylinder. Also, blowby flashing tends to make the upper closure ram stick within the mold cylinder. Once open, any residual material or “flashing” left on the upper ram of the closure device must be cleaned prior to sliding the upper ram back into the bore of the mold cylinder.